This invention relates to thermally conductive material and, more particularly, it relates to a carbon fiber reinforced resin matrix for use as a strong, structurally stable thermal conductive material.
The market segment for electrical devices such as for windings of motors, transformers and solenoids is increasingly moving to miniaturization of such devices. This in turn leads to a rise in internal equipment operating temperature resulting in not only a need for higher temperature ratings on insulation materials used for these applications, but also a need for materials with improved thermal conductivity properties.
It is known to attempt to improve thermal conductivity by adding many kinds of filler as disclosed in "Thermally Conductive Polymer Compositions", D. M. Bigg, Polymer Composites, June 1986, Vol. 7, No. 3, pp. 125-140. The fillers include spherical particles of various metals, glass or carbon black, non-spherical metal or ceramic particles and aluminum fibers. Bigg teaches that the thermal conductivity of the composite is largely determined by the resin and that in the case of fibers, the most important variables influencing composite conductivity are fiber volume fraction and fiber 1/d in the actual composite.